Method for producing 6,10 and 6,9-dimethyl-5,10-undecadienyl-2-ones

ABSTRACT

The present application refers to a process for preparing 6,10- and 6,9-dimethyl-5,10-undecadienyl-2-ones by telomerizing isoprene with alkyl acetoacetates in the presence of a catalyst system containing a transition metal compound catalyst and a phosphorus- or arsenic-containing compound cocatalyst, wherein the process is performed in the presence of a protic additive of the general formula                    
     in which: 
     R 1 , R 2 , R 3  represent an alkyl group with 1 to 9 carbon atoms, branched or unbranched, a cycloalkyl group with 6 to 8 carbon atoms, an aryl group, in particular phenyl, or an arylalkyl group, 
     X (−)  represents an inorganic or organic anion, 
     y is 1 or 2, 
     and the β-ketoester so obtained is saponified and decarboxylated in a manner known per se.

BACKGROUND OF THE INVENTION

The invention relates to a process for preparing 6,10- and 6,9-dimethyl-5,10-undecadienyl-2-ones by telomerizing isoprene with alkylacetoacetates using transition metal compounds as catalysts, followed by saponification and decarboxylation of the β-ketoester obtained.

When using the asymmetric diene, isoprene, there are 12 possible telomeric products, taking into account the linkage pattern of isoprene units in the direction of attack of the nucleophile in the 1, or 3 position and the E,Z-isomerism of the internal double bond. This number is potentiated by using a nucleophile with several acid hydrogen atoms.

Of the 12 possible telomeric products, three have the desired head-to-tail linkage pattern analogous to that in naturally occurring products.

Hitherto, processes disclosed in the prior art have only led to products in which a very small percentage of this type of telomer, if any, can be detected. A process for the preparation of octadienyl hydrocarbon chains is known from J. Berger, J. für prakt. Chem. 327 (1985) 634. Selectivities relating to head-to-tail linkages of <8% are obtained using the route described there.

In G. Hata, J. Org. Chem. 1971 (15), 2116 and Zakharkin et 30 al., Zh. Org. Khim. 1988, (24) 2325, no reference is made to the production of compounds with the desired heads-to-tail linkage when using the reaction mentioned.

Compounds of this type, in particular α-geranylacetone, however, are of great importance as key components for the synthesis of vitamin E.

OBJECT OF THE INVENTION

The object of the invention is to provide a process in which this compound and also related compounds are obtained, these having been proven to be valuable intermediates.

SUMMARY OF THE INVENTION

The invention provides a process for preparing 6,10- and 6,9-dimethyl-5,10-undecadienyl-2-ones by telomerizing isoprene with alkyl acetoacetates in the presence of a catalyst system consisting of transition metal compound catalyst and a phosphorus- or arsenic-containing compound cocatalyst, characterized in that the process is performed in the presence of a protic additive of the general formula:

in which:

R¹, R², R³ represent an alkyl group with 1 to 9 carbon atoms, branched or unbranched, a cycloalkyl group with 6 to 8 carbon atoms, an aryl group, a phenyl, or an arylalkyl group,

X⁽⁻⁾ represents an inorganic or organic anion, in particular halide or sulfate,

y is 1 or 2

and the β-ketoester so obtained is saponified and decarboxylated in a manner known per se. The invention provides 6,10-isomers in particular.

DETAILED DESCRIPTION

In the process of the present invention aliphatic carboxylic acids with 1 to 6 carbons, arylsulfonic acids or alkylsulfonic acids can be used in addition to or instead of the protic additives in accordance with formulae (I) or (II).

Organic solvents are optionally used and are not restricted to specific compounds, with the exception of the general principle that they behave in an inert manner, in the sense of a chemical reaction.

Thus, a protonizing effect is not intended, as is the case, for example, with alcohols of the general formula (I) in the present reaction.

The solvents are also used in the form of mixtures, wherein compounds in accordance with formula (I) act simultaneously as protic additives and as solvents. For example, the present process can be performed in the presence of an organic solvent. Aromatic solvents such as benzene, toluene or phenol, and also alkyl-substituted phenols, ketones and aliphatic alcohols, are suitable solvents.

In a specific embodiment, the compound of the Formula (I), optionally mixed with non-protic solvents, is used a solvent.

Alkyl acetoacetates useful in the present invention are those represented by the general formula

in which

R represents a C₁-C₄ alkyl group, branched or unbranched.

In the present invention, it is preferred that at least two equivalents of isoprene are reacted with one equivalent of an alkyl acetoacetate of formula (III).

The present catalyst system consists of a transition metal from groups 9 and 10 of the Periodic System of Elements (IUPAC 1985) or compounds thereof, and a cocatalyst consisting of a compound of the general formula

A (R⁴ R⁵ R⁶)  (IV)

in which

R⁴, R⁵, R⁶ are identical or different and represent an alkyl or alkoxy group with 1 to 8 carbon atoms, branched or unbranched, a cycloalkyl group with 6 to 8 carbon atoms, an aryl group, in particular phenyl, optionally substituted, preferably substituted in the 2-position and/or 5-position with an alkyl group, an arylalkyl group, or hydrogen;

A represents phosphorus or arsenic.

Preferably, at least one of the substituents R⁴, R⁵, R⁶ is itself substituted by one of the groups comprising OH, —NR¹H, NR¹R²H(⁺) or —COOH, wherein R¹ and R² are defined in the same way as above.

Phosphorus- or arsenic-containing compounds in accordance with formula (IV) are preferably used as cocatalysts, in which at least one of the substituents represents an alkoxy group, in particular a C₃ group. 1 to 10 equivalents of phosphorus- or arsenic-containing compounds according to Formula IV are used to one equivalent of the transition metal or its ions.

The transition metal catalyst useful in the present process is used in an amount sufficient to provide up to 10⁻⁴ to 1 g atom/l of elemental metal. Examples of transition metal compounds or transition metal ligands useful as catalysts in the present process are acetate, carboxylate, carbonate, borate, citrate, bromide, chloride, iodide, hydroxide, nitrate, sulfate, arylsulfonate, alkylsulfonate, acetylacetonate, palladium bis-benzonitrile or potassium tetrapalladate. A palladium-containing compound is particularly preferred in the present invention.

The reaction of the present invention is optionally performed in the presence of a compound, which acts as a reducing agent for the transition metal. Examples of such reducing agent are sodium borohydride, potassium borohydride, zinc powder or magnesium. In combination with isopropanol as solvent, particularly high selectivities are obtained.

In a specific embodiment of the present invention, the 6,10-dimethyl-5,10-undecadienyl-2-one and 6,9-dimethyl-5,10-undecadienyl-2-one are separated from the reaction mixture.

In these cases, Pd acetate is used as the catalyst. The 3-head-to-tail isomers produced in addition to the selectively prepared α-geranylacetone (1-head-to-tail) is another valuable product of this reaction.

Optionally, it has proven advantageous to perform the process in several phases in order, for example, to be able to separate the catalyst or the product(s) more easily.

The selectivities can be controlled by suitable combinations of temperature, solvent and cocatalyst.

The process of the present invention is performed at a temperature of from 0° C. to 130° C., in particular of from 60°C. to 100° C.

EXAMPLE 1

Using a protective gas technique (Ar)-, 11.2 mg (0.05 mmol) of palladium acetate and 39.3 mg (0.15 mmol) of triphenyl phosphane were transferred at 0° C. with 20 ml of i-propanol into a 50 ml glass autoclave with a magnetic stirring rotor. The homogeneous, yellow solution obtained after the addition of 6 g of ethyl acetoacetate and 6.5 g of isoprene was stirred for 3 h at 80° C. and then cooled to room temperature in an ice bath. Then the excess isoprene was removed at room temperature under a water-jet vacuum.

The ethyl-2-(dimethyloctadienyl)-β-ketoesters contained in the reaction mixture were saponified and decarboxylated without further processing. For this purpose, the reaction mixture was stirred for 16 h at room temperature, after adding 3.8 g of sodium hydroxide, 15 ml of water and 30 ml of methanol. After the majority of the solvent had been removed on a rotary evaporator at 80° C., 30 ml of water and 6.4 g of concentrated sulfuric acid were added to the mixture and heated under reflux until no more carbon dioxide was produced (about 1 hour). After extracting three times, using 5 ml of toluene each time, the combined extracts were dried over sodium sulfate. Gas chromatographic analysis of the crude product showed a yield of isogeranylacetones of 29% (with respect to the isoprene used) with a selectivity for 6,10-dimethyl-5,10-undecadien-2-one of 30% (with respect to the telomer fraction).

EXAMPLES 2-40

The same procedure was used as described in Example 1. The addition of 20 ml of i-propanol used there was replaced by 20 ml of another compound, in accordance with Table 1, each time. Against this is plotted the turn-over number mol_(product) mol_(pd) ⁻¹), TON, and the selectivity for 6,10-dimethyl-5,10-undecadien-2-one, 1-HT, with respect to the telomer fraction.

Table 1: Turn-over numbers mol_(product) mol_(pd) ⁻¹) and head-to-tail selectivities (with respect to the telomer fraction) as a function of the additive used and the reaction temperature (n_(Pd):n_(P):n_(acetate):n_(isoprene)=1:3:920:1920, t=3 h).

EXAMPLES 41-69

The same procedure was used as described in Example 1. The addition of 20 ml of i-propanol used there was replaced by 20 ml of a compound, in accordance with the table. Triphenyl phosphane was replaced by another phosphorus compound in accordance with the table. Against this is plotted the turn-over number {mol_(product) mol_(Pd) ⁻¹), TON, and the selectivity for 6,10-dimethyl-5,10-undecadien-2-one, 1-HT, with respect to the telomer fraction.

Table 2: Turn-over numbers {mol_(product) mol_(Pd) ⁻¹) and head-tail selectivities (with respect to the telomer fraction} as a function of the phosphorus compound and additive used (n_(Pd): n_(P): n_(acetate): n_(isoprene)=1:3:920:1920, t=3 h).

TABLE 1 Proportion of telomer fraction/% Example Cocatalyst T ° C. Reaction medium 1HT 1TT 1TH 1HH 3HT 3TT Other ton  2 PPh3 80 Acetone 4.2 86.6 4.6 0.4 0.7 3.0 0.6 298  3 PPh3 80 Toluene 3.3 83.6 3.3 0.3 0.0 2.8 6.5  29  4 PPh3 80 Isoprene 3.3 83.9 3.0 0.7 0.4 2.7 6.0  31  5 PPh3 80 t-pentanol 24.0 59.1 10.1 1.1 3.4 2.0 0.3 276  6 PPh3 80 Methylene chloride 15.5 65.6 11.7 1.1 2.8 2.5 0.8 102  7 PPh3 80 t-butanol 27.1 53.7 11.9 1.3 3.5 1.9 0.5 371  8 PPh3 80 Acetonitrile 18.4 61.2 13.0 1.2 2.7 2.6 0.9 173  9 PPh3 80 n-pentanol 28.0 36.8 26.9 3.8 2.7 1.2 0.7 401 10 PPh3 80 I—PrOH/H2O 18.6 43.6 31.2 4.0 1.4 0.7 0.5  59 11 PPh3 80 Pinacol 27.2 32.6 30.6 5.0 2.2 1.4 0.9 123 12 PPh3 80 Ethanol 28.3 30.7 32.1 5.7 1.8 1.1 0.4 207 13 PPh3 80 Methanol 16.0 25.3 47.0 8.3 0.8 0.8 1.7  42 14 PPh3 80 Phenol 1.0 1.0 80.7 17.4 0.0 0.0 0.0  6 15 PPh3 80 2,6-dimethylphenol 1.6 6.9 53.0 27.3 0.0 1.9 9.3 197 16 PPh3 80 2,3-butanediol 10.9 0.9 39.5 40.0 0.0 0.0 8.7 n.d. 17 PPh3 80 t-butylphenol 2.7 4.3 36.9 54.4 0.0 0.0 1.7 150 18 PPh3 80 i-propylphenol 1.6 1.7 25.4 58.1 0.0 0.0 13.2 157 19 PPh3 80 2,4,6- n.d. n.d. n.d. n.d. n.d. n.d. 100a  <2 trichlorophenol 20 PPh3 80 Propionic acid n.d. n.d. n.d. n.d. n.d. n.d. 100a  <2 21 PPh3 50 i-propanol n.d. n.d. n.d. n.d. n.d. n.d. n.d.  <1 22 PPh3 60 i-propanol 5.8 11.8 66.3 10.4 0.0 0.0 5.8  2 23 PPh3 70 i-propanol 22.3 19.5 39.7 6.5 1.8 1.2 9.0  16 24 PPh3 75 i-propanol 26.0 22.9 36.0 5.8 1.6 0.8 7.0  30 25 PPh3 85 i-propanol 28.4 39.6 23.5 3.1 2.8 1.5 1.2 396 26 PPh3 90 i-propanol 30.5 39.5 21.8 2.9 2.8 1.6 0.9 247 27 PPh3 70 t-pentanol 29.4 38.5 19.1 2.5 2.4 1.3 6.7a 28 PPh3 50 t-butanol 27.9 24.9 34.5 5.7 2.2 1.0 3.9  27 29 PPh3 60 t-butanol 32.6 35.8 23.5 3.1 3.5 1.2 0.4 159 30 PPh3 70 t-butanol 31.0 44.1 17.1 1.9 3.9 1.5 0.6 2B6 31 PPh3 90 t-butanol 18.2 65.9 9.3 1.0 2.3 2.3 1.0 458 32 PPh3 60 n-pentanol 24.3 26.6 37.7 8.7 1.6 1.2 0.0  52 33 PPh3 70 n-pentanol 28.0 27.7 34.9 6.3 2.0 1.2 0.0 134 34 PPh3 85 n-pentanol 28.0 36.8 26.9 3.8 2.7 1.2 0.7 401 35 PPh3 90 n-pentanol 28.8 41.9 22.9 2.9 0.6 1.6 0.7 425 36 PPh3 60 Ethanol 27.1 27.6 35.2 7.3 1.3 0.9 0.9  23 37 PPh3 70 Ethanol 26.2 27.6 35.9 7.1 1.5 1.0 0.5  87 38 PPh3 90 Ethanol 27.0 36.1 28.4 4.0 2.2 1.4 1.0 425 39 PPh3 60 i-propylphenol 0.0 0.0 0.0 13.5 0.0 0.0 86.5  3 40 PPh3 70 i-propylphenol 0.8 2.3 15.5 51.8 0.0 0.0 29.5  21

TABLE 2 Proportion of telomer fraction/% Example Cocatalyst T ° C. Reaction medium 1HT 1TT 1TH 1HH 3HT 3TT Other ton 41 P(CH2CH2CH2CH3)3 80 Aceton 15.7 38.0 36.2 5.3 1.5 1.8 1.6  70 42 PPh(CH2CH2CH3)2 80 Acetone 18.1 50.6 23.9 1.8 2.0 1.9 1.7 138 43 PPh2(CH2CH2CH3) 80 Acetone 17.3 51.7 23.1 2.1 1.7 1.7 2.5  99 44 PPh(OCH2CH2CH2CH3)2 80 Acetone 12.5 66.4 7.7 0.9 0.9 1.2 10.5 298 45 PPh2(OCH2CH2CHCH3) 80 Acetone 4.0 83.7 6.5 0.5 0.4 2.0 2.8  69 46 P(OCH2CH2CH2CH3)3 80 Acetone 19.0 72.6 3.5 0.4 1.3 3.0 0.2 408 47 2-PPh₂cyclopentanol 80 Acetone 4.9 75.3 13.8 1.2 1.1 1.8 2.0  42 48 P(Ph)₂(CH₂CH₂CH₂OH) 80 Acetone 20.3 56.5 16.5 1.6 2.0 1.9 1.0  75 49 P(CH2CH2CH2CH3)3 80 i-propanol 8.9 9.1 51.8 19.8 0.8 0.7 8.7 555 50 P(o-anisyl)3 80 i-propanol 15.7 21.2 36.4 26.4 0.2 0.0 0.1  24 51 P(p-Me2NC6H4)3 80 i-propanol 10.9 23.0 44.4 20.8 0.3 0.0 0.6  12 52 PPh(CH2CH2CH3)2 80 i-propanol 12.5 15.1 59.9 12.5 0.0 0.0 0.0  3 53 PPh2(CH2CH2CH3) 80 i-propanol 28.5 26.6 31.9 7.0 1.7 0.8 3.4 264 54 P(p-tol)3 80 i-propanol 28.6 28.6 33.5 6.0 1.6 1.2 0.6  72 55 PPh(OCH2CH2CH2CH3)2 80 i-propanol 41.9 33.3 18.7 2.8 2.2 0.8 0.2 216 56 PPh2(OCH2CH2CHCH3) 80 i-propanol 27.6 49.4 16.3 1.7 2.6 0.7 1.7 396 57 P(OCH2CH2CH2CH3)3 80 i-propanol 39.5 40.0 14.4 1.6 2.9 1.6 0.0 540 58 P(OEt)3 80 i-propanol 35.1 47.0 12.1 1.4 2.9 1.1 0.5 262 59 P(O-i-octyl)3 80 i-propanol 36.3 47.7 10.0 1.1 2.8 1.6 0.4 468 60 P(OCH2)3CCH3a) 80 i-propanol 36.8 50.6 7.4 0.8 2.8 1.3 0.2 129 61 P(OCH2)3CCH2OHb) 80 i-propanol 34.9 52.8 7.0 0.8 2.8 1.1 0.5 229 62 P(OCH2)3CCH2OH 80 i-propanol 34.9 52.8 7.0 0.8 2.8 1.1 0.5 459 63 P(OPH)₃ 80 i-propanol 18.6 72.9 5.2 0.5 1.2 0.5 1.1 272 64 P(CH₂CH₂CN)₃ 80 i-propanol n.d. n.d. n.d. n.d. n.d. n.d. n.d.  <2 65 P(Ome)₃ 80 i-propanol n.d. n.d. n.d. n.d. n.d. n.d. n.d.  <2 66 P(O-2,6- 80 i-propanol n.d. n.d. n.d. n.d. n.d. n.d. n.d.  <2 dimethylphenyl)₃ 67 P(pentafluorophenyl)₃ 80 i-propanol n.d. n.d. n.d. n.d. n.d. n.d. n.d.  <2 68 P(OCH₂CF₃)₃ 80 i-propanol n.d. n.d. n.d. n.d. n.d. n.d. n.d.  <2 69 Pd(P(OCH₂)₃CCH₂OH)₄ 80 i-propanol 24.6 64.9 2.6 4.0 1.8 1.7 0.3 111 70 ppH₂(O—H—C₆H₄) 80 i-propanol n.d. n.d. n.d. n.d. n.d. n.d. n.d.  <2

TABLE 3 Formulation same as in examples 41-70, with variable temperature Proportion of telomer fraction/% Example Cocatalyst T ° C. Reaction medium 1HT 1TT 1TH 1HH 3HT 3TT Other ton 71 P(Obu)3 50 EtOH 17.2 16.8 39.9 26.1 0.0 0.0 0.0  2 72 P(Obu)3 60 EtOH 22.5 24.3 36.7 16.5 0.0 0.0 0.0  2 73 P(Obu)3 70 EtOH 9.1 6.4 53.8 10.2 0.5 0.8 19.1  29 74 P(Obu)3 90 EtOH 23.0 32.3 36.8 4.1 1.7 0.7 1.4 446 75 P(Obu)3 80 t-butanol 15.0 75.1 5.6 0.6 1.1 9.0 1.6 456 76 P(Obu)3 90 t-butanol 32.7 55.9 5.9 0.7 2.1 2.3 0.4 512 77 P(Obu)3 90 2-propanol 34.4 49.8 10.1 1.0 2.5 1.4 0.6 377 78 P(Obu)3 70 t-butanol 40.9 43.5 9.5 1.2 2.7 1.8 0.3 305 79 P(Obu)3 70 2-propanol 40.5 35.5 16.0 2.0 3.3 1.5 1.3 326 80 P(Obu)3 60 2-propanol 38.0 32.9 18.2 2.2 2.7 1.3 4.8 357 81 P(Obu)3 50 t-butanol 41.2 33.2 18.5 2.7 2.8 1.3 0.3  92 82 P(Obu)3 50 2-propanol 31.9 24.6 32.6 7.1 2.0 1.0 0.7  68 83 P(Obu)3 60 t-butanol 21.4 19.4 23.4 29.6 0.0 0.0 6.2  3 84 P(OCH2)3CCH2OH 50 Ethanol 4.5 4.5 44.3 46.6 0.0 0.0 0.0  1 85 P(OCH2)3CCH2OH 60 Ethanol 36.1 38.5 22.7 2.7 0.0 0.0 0.0  24 86 P(OCH2)3CCH2OH 70 Ethanol 23.6 24.7 26.0 13.5 1.4 1.2 9.6  26 87 P(OCH2)3CCH2OH 80 Ethanol 26.1 26.1 21.4 10.2 1.5 1.3 13.5  34 88 P(OCH2)3CCH2OH 90 Ethanol 36.7 43.2 1.8 3.3 2.4 1.0 0.6 123 89 P(OCH2)3CCH2OH 50 2-propanol 30.0 27.7 23.4 6.8 2.2 1.0 8.7  25 90 P(OCH2)3CCH2OH 60 2-propanol 38.4 37.5 12.7 1.7 3.0 1.2 5.5  69 91 P(OCH2)3CCH2OH 70 2-propanol 39.0 43.9 8.6 1.1 2.7 1.3 3.4 106 92 P(OCH2)3CCH2OH 90 2-propanol 33.6 56.8 5.0 0.7 2.0 1.5 0.3 511 93 P(OCH2)3CCH2OH 80 Methanol 5.0 12.9 48.8 27.6 0.0 0.0 5.6  8 94 P(OCH2)3CCH2OH 50 t-butanol 35.4 37.3 11.8 8.1 2.3 1.1 4.0  20 95 P(OCH2)3CCH2OH 60 t-butanol 36.4 45.7 7.4 4.4 2.6 1.3 2.2 631 96 P(OCH2)3CCH2OH 70 t-butanol 34.8 52.4 5.0 1.4 2.5 1.5 2.5 105 97 P(OCH2)3CCH2OH 80 t-butanol 30.0 61.1 3.3 0.9 2.1 1.9 0.7 123 98 P(OCH2)3CCH2OH 90 t-butanol 23.8 68.4 3.2 0.6 1.8 2.0 0.3 404

TABLE 4 Formulation same as in examples 1, with variable telogens and solvents Proportion of telomer fraction/% Example Reaction medium Telogen 1HT 1TT 1TH 1HH 3HT 3TT Other ton  99 Acetone CH₃COCH₂COOCH₃ 10.6 45.4 24.9 1.9 2.0 2.4 12.6  14 100 Acetone CH₃COCH₂COOC(CH₃)₃ 5.3 34.3 12.6 2.1 2.9 0.0 42.7  30 101 Acetone (CH₃CO)₂CHCOOCH₃ 9.7 21.7 54.8 5.6 0.0 1.1 7.1  31 102 i-PrOH CH₃COCH₂COOCH₃ 24.9 28.4 35.8 6.2 2.3 1.1 1.4 150 103 i-PrOH CH₃COCH₂COOC(CH₃)₃ 20.3 38.1 33.2 3.9 0.2 0.7 3.5  86 104 i-PrOH (CH₃CO)₂CHCOOCH₃ 7.8 16.1 56.5 14.9 0.0 0.0 4.7  18

TABLE 5 Formulation same as in examples 1, with variable solvent telogen concentration Proportion of telomer fraction/% Example Reaction medium acetate:Pd 1HT 1TT 1TH 1HH 3HT 3TT Other ton 105 i-PrOH  200:1 21.9 28.3 36.8 5.4 1.4 1.2 2.0 14 106 i-PrOH  400:1 28.9 27.7 30.5 5.4 0.4 1.0 3.0 65 107 i-PrOH 1800:1 28.5 24.6 27.2 4.6 0.2 0.5 10.8 88 108 i-PrOH 2500:1 26.4 23.7 25. 4.4 2.3 0.6 13.9 46 109 i-PrOH 3400:1 21.1 14.9 23.5 3.7 1.1 2.7 30.5 13 110 Acetone  400:1 6.7 68.3 6.0 0.9 0.5 2.5 15.2 a 111 Acetone  500:1 10.3 68.7 6.1 0.0 0.0 1.9 13.0 a 112 Acetone 1600:1 16.4 32.9 22.3 2.4 1.3 1.1 23.6 a 113 Acetone 3600:1 17.5 45.0 18.4 1.5 2.8 2.1 12.7 a Solvent + telogen = 25 ml, a ton was not determined

TABLE 6 Formulation same as in examples 1, with variable cocatalyst and Pd/P ratio Proportion of telomer fraction/% Example Cocatalyst Pd/P 1HT 1TT 1TH 1HH 3HT 3TT Other ton 114 P(OCH2)3CCH2OH a 1/1.2 29.3 61.1  5.8 0.7 1.9 0.4 0.9 313 115 P(OCH2)3CCH2OH a 1/2.1 35.6 53.6  5.9 0.8 2.7 1.1 0.4 518 116 P(OCH2)3CCH2OH a 1/4.7 24.3 26.7 12.8 21.2  0.0 0.0 15.1   5 117 P(OCH2)3CCH2OH a 1/6.7 n.d. n.d. n.d. n.d. n.d. n.d. n.d.  <1 118 P(OBu)3 1/1.9 37.1 37.1 15.4 1.7 2.8 1.0 1.2 277 119 P(OBu)3 1/4.0 39.7 39.7 17.7 2.2 2.7 1.4 0.8 344 120 P(OBu)3 1/5/7 28.6 28.6 18.4 3.2 1.6 1.6 25.9   6 a t = 1 h 

What is claimed is:
 1. A process for preparing 6,10- and 6,9- dimethyl-5,10-undecadienyl-2-ones by telomerzing isoprene with alkyl acetoacetates in the presence of a catalyst system containing a transition metal compound catalyst and a phosphorus- or arsenic-containing compound cocatalyst, wherein the process is performed in the presence of a protic additive of the general formula

in which: R¹, R², R³ represent an alkyl group with 1 to 9 carbon atoms, branched or unbranched, a cycloalcyl group with 6 to 8 carbon atoms, an aryl group, or an arylalkyl group, X⁽⁻⁾ represents an inorganic or organic anion, y is 1 or 2, and the β-ketoester so obtained is saponified and decarboxylated in a manner known per se.
 2. The process according to claim 1, wherein aliphatic carboxylic acids with 1 to 6 carbon atoms, arylsulfonic acids or alkysulfonic acids are used in addition to, or instead of, the protic additives of formulae (I) or (II).
 3. The process according to claim 1, wherein at least two equivalents of isoprene are reacted with one equivalent of an alkyl acetoacetate of the general formula

in which R represents a C₁-C₄ alkyl group, branched or unbranched.
 4. A process according to claim 1, wherein, the catalyst system consists of a transition metal compound from groups 9 and 10 of the Periodic System of Elements (ITUPAC 1985), and a cocatalyst consisting of a compound of the general formula A (R⁴ R⁵ R⁶)  (IV) in which R⁴, R⁵, R⁶ are identical or different and represent an alkyl or alkoxy group with 1 to 8 carbon atoms, branched or unbranched, a cycloakyl group with 6 to 8 carbon atoms, an aryl group, optionally substituted, an arylalkyl group, or hydrogen; A represents phosphorus or arsenic.
 5. The process according to claim 4, wherein at least one of the substituents R⁴, R⁵, R⁶ is itself substituted by one of the substituents selected from the group consisting of —OH, —NR¹H, —NR¹R²H(⁺) and —COOH.
 6. A process according to claim 1, wherein an acetate, carboxylate, carbonate, borate, citrate, bromide, chloride, iodide, hydroxide, nitrate, sulfate, arylsulfonate, acetylacetonate is used as a transition metal ligand in a transition metal compound.
 7. The process according to claim 1, wherein the reaction is performed in the presence of a compound which acts as a reducing agent for the transition metal.
 8. The process according to claim 7, wherein the reducing agent is selected from the group consisting of sodium borohydride, potassium borohydride, zinc powder or magnesium.
 9. The process according to claim 4, wherein 1 to 10 equivalents of one or more compounds according to formula IV are used to one equivalent of said transition metal.
 10. The process according to claim 7, wherein the amount of said transition metal used for the reaction is sufficient to provide up to 10⁻⁴ to 1 g atom/l of elemental metal.
 11. The process according to claim 1, wherein the reaction is performed at a temperature of from 0° C. to 130° C.
 12. The process according to claim 1, wherein the process is performed in an organic solvent.
 13. The process according to claim 12, wherein a compound of the formula (I), optionally mixed with non-protic solvents, is used as solvent.
 14. The process according to claim 1, wherein the 6,10-dimethyl-5,10-undecadienyl-2-one and 6,9-dimethyl-5,10-undecadienyl-2-one are separated from the reaction mixture.
 15. The process according to claim 4, wherein the aryl group is unsubstituted phenyl.
 16. The process according to claim 4, wherein the aryl group is a phenyl substituted in the 2-position and/or 5-position with an alkyl group.
 17. The process according to claim 6, wherein the transition metal compound contains palladium.
 18. The process according to claim 1, wherein the reaction is performed at a temperature of from 60° C. to 100° C.
 19. The process according to claim 1, further comprising saponifying and decarboxylating the β-ketoester.
 20. A process for preparing 6,10- and 6,9-dimethyl-5,10-undecadienyl-2-ones by telomerizing isoprene with alkyl acetoacetates in the presence of a catalyst system containing a transition metal compound catalyst and a phosphorus- or an arsenic-containing compound cocatalyst, wherein the process is performed in the presence of an acid or a protic additive of the general formula:

in which: R¹, R², R³ are selected from the group consisting of an alkyl group with 1 to 9 carbon atoms, branched or unbranched, a cycloalkyl group with 6 to 8 carbon atoms, an aryl group, a phenyl group, and an arylalkyl group, X⁽⁻⁾ represents an inorganic or organic anion, y is 1 or 2 to form an enhanced yield of an 11-membered β-ketoester. 